Prefetching variable length data
First Claim
1. An interface unit connected between a first bus and a second bus, said first bus having connected thereto a memory system and said second bus having connected thereto a plurality of devices which perform read operations directed at said memory system, said interface unit comprising:
- a buffer memory having an input that is electrically coupled to the first bus for receiving data that is sent from said memory system over said first bus and an output that is electrically coupled to said second bus for delivering data to said second bus for transfer to a requesting device, said requesting device being one of said plurality of devices;
a plurality of prefetch size registers equal in number to said plurality of devices, wherein each of said plurality of prefetch size registers stores a number for a different corresponding one of said plurality of devices, wherein the number stored in each of said plurality of prefetch size registers specifies an amount of data that is prefetched from memory in response to a data read request from the corresponding device; and
a control unit which in response to a data read request from any one of said plurality of devices prefetches into said buffer a predetermined amount of data from said system memory, said predetermined amount being determined by the number stored in the prefetch size register corresponding to the requesting device.
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Accused Products
Abstract
An interface unit connected between a first bus and a second bus, the first bus having connected thereto a memory system and the second bus having connected thereto a plurality of devices which perform read operations directed at the memory system, the interface unit including a buffer memory having an input that is electrically coupled to the first bus for receiving data that is sent from the memory system over the first bus and an output that is electrically coupled to the second bus for delivering data to the second bus for transfer to a requesting device, the requesting device being one of the plurality of devices; a plurality of prefetch size registers equal in number to the plurality of devices, wherein each of the plurality of prefetch size registers stores a number for a different corresponding one of the plurality of devices, wherein the number stored in each of the plurality of prefetch size registers specifies an amount of data that is prefetched from memory in response to a data read request from the corresponding device; and a control unit which in response to a data read request from any one of the plurality of devices prefetches into the buffer a predetermined amount of data from the system memory, the predetermined amount being determined by the number stored in prefetch size register corresponding to the requesting device.
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Citations
14 Claims
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1. An interface unit connected between a first bus and a second bus, said first bus having connected thereto a memory system and said second bus having connected thereto a plurality of devices which perform read operations directed at said memory system, said interface unit comprising:
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a buffer memory having an input that is electrically coupled to the first bus for receiving data that is sent from said memory system over said first bus and an output that is electrically coupled to said second bus for delivering data to said second bus for transfer to a requesting device, said requesting device being one of said plurality of devices; a plurality of prefetch size registers equal in number to said plurality of devices, wherein each of said plurality of prefetch size registers stores a number for a different corresponding one of said plurality of devices, wherein the number stored in each of said plurality of prefetch size registers specifies an amount of data that is prefetched from memory in response to a data read request from the corresponding device; and a control unit which in response to a data read request from any one of said plurality of devices prefetches into said buffer a predetermined amount of data from said system memory, said predetermined amount being determined by the number stored in the prefetch size register corresponding to the requesting device. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of prefetching data in a system including a first bus to which a memory system is connected and a second bus to which a plurality of devices are connected, said method comprising:
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providing a plurality of prefetch size registers equal in number to said plurality of devices, each of said prefetch size registers corresponding to a different one of said devices; storing a plurality of prefetch amounts in said plurality of prefetch registers, each prefetch amount of said plurality of prefetch amounts being stored in a different corresponding one of said prefetch size registers; in response to receiving a data read request from one of said plurality of devices, reading the prefetch amount that is stored in the prefetch register which corresponds to the requesting device; prefetching a predetermined amount of data from said system memory over the first bus, said predetermined amount being equal in size to the prefetch amount for the requesting device; storing the prefetched data in a buffer; and transferring the prefetched data from the buffer to the requesting device over the second bus. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification